import time

def say_hello():
    # 此程序比较耗时，大约需要 10 秒完成
    for x in range(10):
        print("hello!!!")
        time.sleep(1)

def say_world():
    for y in range(10):
        print('world...')
        time.sleep(1)

# 调用
say_hello()  # ???   10?   20?
say_world()  # ???
